The Comparison of Four Economical Selection Indices for Improving the Performance of Kermani Sheep under Rural Production System

Developing effective selection programs for improving the performance of livestock requires taking the economical selection indices into account. The present study was performed for comparing four selection indices developed in Kermani sheep through simulated data. The relative importance of traits was determined based on the estimated economic values and consequently, the most beneficial traits were applied to develop the selection indices. The considered selection indices were different combinations of traits including ewe body weight (EBW), annual wool weight (AWW) and total weaning weight of lambs per exposed ewe (TWWEE). The first index included all three mentioned traits (EBW, AWW, and TWWEE). The second, third and fourth indices were included (AWW, TWWEE), (EBW, TWWEE) and (TWWEE), respectively. In general, the obtained results indicated that under all the developed selection indices the aggregate genotype, selection index and economic progress increased by increasing in the population size and decreasing in ram ratio, but resulted in reduced inbreeding average. In more cases, the aggregate genotype decreased by removing a trait from the index. The comparisons among indices indicated that the most suitable selection index for this breed under rural production system is the first index which included EBW, AWW, and TWWEE. This index had a maximum selection index average, aggregate genotype, and economic progress.